1. Field of the Invention
This invention relates to computer software. More particularly, this invention relates to a representation of computer program instructions in a form suitable for post-link optimization.
2. Description of the Related Art
Post-link optimization tools are widely used today for applying a wide range of optimizations on executable files in order to improve performance, reduce power consumption and improve space utilization.
Optimizations applied directly to post-linked program executables have been shown to be highly effective in producing significant performance gain. Large programs tend to be compiled using separate compilation units, i.e., one or several files at a time. As a result, a compiler cannot fully realize transformations and optimizations applied on the program as a whole, even when performing sophisticated interprocedural analysis. For example, global code reordering is an optimization, which is suitable to be applied at the post-link stage.
Furthermore, some program information is not known until completion of the linkage build stage, e.g., the final location of global variables. As a result, some optimizations, such as global data reordering and other optimizations that follow global data restructuring, are most effective when applied to the final program file.
U.S. Pat. No. 6,021,272, issued to Cahill, et al., proposes transforming and manipulating program object code. A set of program object code is transformed into a platform-independent form. The platform-independent form of the object code is represented as a linked list of pseudo-assembly code instructions, with each such instruction coupled to a set of symbol and relocation tags for that instruction. A platform-independent assembly code manipulator inserts, deletes, and rearranges, and modifies instructions. Afterward, a reassembler may produce new object code from the platform-independent assembly code.